textproduct: Quad Cities

KEY MESSAGES

- There is a Slight (level 2 out of 5) risk for severe storms this morning and early afternoon. Damaging wind up to the 70 mph and heavy rain will be the primary threats. Some embedded tornadoes will also be possible.

- There is a Marginal (level 1 out of 5) risk for severe storms Thursday afternoon and evening. Damaging wind and heavy rain will be the primary threats. Some localized flash flooding is also possible for areas that see repeating storms.

- There will be a near daily risk of shower/storms through the remainder of the week and into the weekend, However, there will also be many hours of dry weather.

UPDATE

Issued at 1058 AM CDT Wed Aug 12 2026

Changes...

The heat advisory has been cancelled for the following counties; In Iowa...Jefferson, Henry and Des Moines In Illinois...Henderson and Warren

Cloud cover combined with continued showers and storms will result in lower temperatures this afternoon.

The heat advisory will continue for our far southern tier of counties but peak heat indices may only get to around 100 degrees.

Discussion...

The first MCS is exiting the area but boundaries are providing numerous foci for additional showers and storms this afternoon. A loose cluster developed in central Iowa that is now moving into eastern Iowa and is expected to persist through the afternoon and into the evening.

The special 12z upper air flight just before the storms has 6200 CAPE. The morning MCS has partially worked over the atmosphere but plenty of potential remains. The current storms across the area still have the potential to produce a localized severe wind gust or hail. Thus the current severe thunderstorm watch will remain in effect for the area.

SHORT TERM /THROUGH TONIGHT/

Issued at 250 AM CDT Wed Aug 12 2026

Another repeat of yesterday? Same llvl thermal and moisture gradient alignment from the northern/central plains over to Indiana, with the local area stuck in the middle. Water vapor imagery showing a seasonably robust short wave probably convectively enhanced, acrs central SD and an associated strong cluster of storms pushing southeast into far north central NE ATTM. This may be the "player" as it continues to evolve and develop a cold pool for propagation mechanics acrs IA and through the local area this morning. Current trends would have it dive further southeast than what most CAMs suggest it will and then hammer the far southern CWA and MO. But these areas are covered by a strong EML, and more prime LLJ feed and ongoing MCS maintenance parameters align right along I-80 into northern IL. Thus would expect more north/northeastward flank development of the current storm cluster as it comes acrs and much of the DVN CWA except maybe the far north will be at risk of the wrath of another severe QLCS with damaging winds and embedded tornadoes this morning.

If the current 3500 J/kg MLCAPE pool can hang on during storm arrival, there appears to be enough kinematics again to fuel wind gusts of 70 to 85 MPH with a bow utilizing cold pool mechanics and mix down. The ongoing quasi-stationary LLVL boundary undulating acrs NE over to northern IL will also be a focus. The storms will also be producing rainfall at rates of 1-2 inches an hour, but hopefully the progressive nature will limit flash flooding potential unless some re-generation of a few storms on the wake outflow left behind lingers longer into early afternoon on areas hit hard earlier.

High temperatures may vary quite a bit with convective debris and outflow boundaries all over the place. But with storm system exit and most the afternoon to recover, looks like another sultry day with high humidity. Went ahead and issued another Heat Advisory for the southern third of the fcst area which is expected remain south of the main boundary and in the land of sfc DPTs in the upper 70s to around 80. Some chance that a further south MCS track and lingering wake clouds/perculating precip may ruin the ambient temp heat up potential even in the south.

Tonight...Signs of another bout of short wave upper ridging and LLJ re-focus back off to the west may make the later afternoon and most of the night precip free again...with the ongoing chance for a rogue elevated shower or storm with nocturnal LLJ WAA processes. This as yet another short wave or MCV lurks upstream off to the west to ruin the day Thursday. Like having to watch for this early Wednesday morning, there may be some fog development in spots Thu morning especially along and north of the quasi-stationary boundary. NBM low temps ranging from the upper 60s to low 70s look on target.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 250 AM CDT Wed Aug 12 2026

Thursday...This could be a day were the rounds of heavy rainfall add up and the flooding potential increases especially by late Thu night. After we may have yet another strong to severe MCS or storm cluster move acrs the area during the day, there are synoptic scale signals that the LLVL west-to-east boundary gets enhanced and is a focus point of LLJ convergence and moisture feed, fueling more thunderstorms possibly in a back-building scenario as Thu night progresses. Where this west-to-east line of convection lays out still uncertain of course at this juncture of the game but CAM ensembles are hinting along to a county or two north of the I-80 corridor. Depending on what occurs rainfall-wise leading up to this scenario, could see the eventual need for a flood watch for Thu or Thu night.

Friday through Tuesday...Latest ensemble and upper jet trends suggest the upper ridge and heat dome to get presses eastward again with some amplitude thrust up the mid to upper MS RVR Valley with west coast L/W troffiness establishment. This could make for another heat and storm track battle zone on Friday for the region, until the track then gets shunted more to the north acrs MN and WI while we heat up again. Still on the southern fringe, couldn't rule out MCS seepage down this far south into the local at times over the weekend as well. The action may last into early next week with longer range signs of upper ridge dampening and flattening to get us back under the influence of ring of fire periphery.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1221 PM CDT Wed Aug 12 2026

Unstable atmosphere will be conducive for isolated to scattered (20-40%) SHRA/TSRA through 00z/13. After 00z/13 isolated SHRA or a TSRA will fester until stronger support arrives after 06z/13 in the form of another thunderstorm complex. Given high moisture and light winds, the potential is there for patchy fog with IFR/LIFR conditions.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory until 8 PM CDT this evening for IAZ098-099. IL...Heat Advisory until 8 PM CDT this evening for ILZ034-035. MO...Heat Advisory until 8 PM CDT this evening for MOZ009-010.